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B Taccardi

Publications and source records attributed to B Taccardi.

At least 73 records · Page 4Linked to original sources
PubMed1982

[Experimental studies on the diffusion of excitation on the right ventricular surface in the dog, during normal and stimulated beats].

Previous work on the spread of excitation on the dog's ventricular surface enabled us to locate up to 30 breakthrough points (BKTPs) where excitation reaches the ventricular surface. In particular the equipotential contour maps enabled us to detect 3 to 5 BKTPs on the anterior right ventricular surface, near the a-v groove when a large part of ventricular surface was still at rest. With a view to investigating the mechanism underlying the early excitation of these basal regions, we stimulated the heart at several right ventricular BKTPs and in other points located at a distance from the BKTPs. The instantaneous equipotential maps showed that after stimulation most right ventricular BKTPs remained in the same position as observed the normal beats. The early appearance of epicardial wavefronts in the basal region and generally in other areas of the right ventricle was attributed to the rapid propagation of excitation waves through the Purkinje network, probably associated to a short transmural crossing time, due to a local thinness of the ventricular wall.

Animals↗
PubMed1981

[Treatment of acute myocardial infarction with verapamil. Hemodynamic effects and electrical changes studied by body surface maps (author's transl)].

The effects of Verapamil on main haemodinamic parameters and on Max sigma pos., sigma Q15, Max sigma pos./Max sigma neg. and sigma ST, studied by automatic recording of thoracic maps, were evaluated in 11 patients with acute myocardial infarction within 6 hours from pain onset. Verapamil was given at the dose of 0.1 mg/Kg followed by infusion of 0.035 mg/min. Hemodynamic measurements were made before and 15 minutes after Verapamil; the maps were recorded before and 5, 15 and 30 minutes after Verapamil. Heart rate and sistolic arterial pressure were reduced, though not significantly: right atrial pressure, pulmonary pressures and capillary pulmonary pressure remained unchanged. On the contrary, the reduction of diastolic arterial pressure (from 94 +/- 4.2 to 88 +/- 4.5 mmHg; P less than 0.05) and of cardiac index (from 3.1 +/- 0.11 to 3 +/- 0.11; P less than 0.05) was important. Max sigma pos. increased after 15 minutes from 11619 +/- 1970 to 12349 +/- 2151 microV (P less than 0.01), but il decreased after 30 minutes to 11037 +/- 2042 microV (P less than 0.05). Max sigma pos./Max sigma neg. ratio increased significantly after 5 and 15 minutes. Sigma Q15 increased significantly only after 30 minutes (from 7198 +/- 1643 to 8688 +/- 1541 microV; P less than 0.05). Sigma ST showed a transient, non significant increase after 5 minutes, but decreased significantly after 30 minutes (from 76664 +/- 19505 to 67157 +/- 18581 microV; P less than 0.05). The results show that Verapamil does not cause worsening of main haemodinamic parameters during acute, non complicated myocardial infarction and reduces significantly ST segment elevation. The Authors discuss also a possible electrophysiological effect of Verapamil on action potential of ischemic cells, responsible for early increase of sigma ST observed in some patients.

Aged↗
PubMed1978

An approach to inverse calculation of epicardial potentials from body surface maps.

The inverse problem of evaluating epicardial potentials from a knowledge of heart and torso geometry as well as body surface potentials is here formulated as a problem in control theory. As is well known, such an inverse problem is ill-posed and a regularization technique has been devised to overrun this difficulty. The resulting regularized problem is well-posed and requires the minimization of a cost function including, besides the square distance of any predicted surface potential distribution from the experimental one, a regularization term involving the second derivatives of the identified epicardial potentials. The results here presented were obtained on a model problem for a plane geometry. Surface potentials generated by multipoles and perturbated with a noise level reflecting both instrumentation and electrode placement uncertainties were fitted by the proposed method and 'epicardial potentials' were determined with a maximum sum square relative error of 15%. The results suggest that by introducing suited regularity constraints, the a priori difficulties inherent to the problem of computing epicardial potentials from torso potentials, can be overcome.

Action Potentials↗
PubMed1976

Body-surface maps of heart potentials: tentative localization of pre-excited areas in forty-two Wolff-Parkinson-White patients.

Heart potentials were recorded from the entire chest surface in 42 patients suffering from Wolff-Parkinson-White syndrome. We were able to identify six types of surface maps, according to the location of the potential maximum and minimum during the delta wave. For each of these types we suggested the most likely location of the pre-excited region around the A-V rings (types 1 to 5) or in the interventricular septum (type 6). In 13 patients belonging to Types 1, 2, 3, 5 and 6 our hypotheses were in agreement with intracardiac recordings, epicardial maps or surgical results obtained by others. Isopotential surface maps provide more information on the location of the pre-excited area than conventional ECGs, particularly when these exhibit intermediate features between Types A and B.

Action Potentials↗